Tuning-fork type quartz vibrators have been used for oscillators and so on. Patent Document 1 cited below discloses a tuning-fork type quartz vibrator 1001 as illustrated in a plan view in FIG. 12.
The tuning-fork type quartz vibrator 1001 includes a base section 1002 and vibrating arm sections 1003, 1004; first end portions of the vibrating arm sections 1003, 1004 are respectively connected to the base section 1002. The base section 1002 and the vibrating arm sections 1003, 1004 are formed through processing a quartz substrate. A plurality of through-holes 1005 are provided in the vibrating arm section 1003 extending in a lengthwise direction thereof.
FIG. 13 is a cross-sectional view taken along a B-B line in FIG. 12. Directions of the electric fields applied to vibrating arm segments on both sides of the through-hole 1005 in the vibrating arm section 1003 are indicated by arrow marks in the drawing, while having a relationship with crystal axes of the quartz substrate as shown in FIG. 13. Further, a first vibration electrode 1006 is provided on each side surface facing the through-hole 1005 and a second vibration electrode 1007 is provided on a side surface of each outer side portion in the vibrating arm segment. Applying alternating electric fields from the first and second vibration electrodes 1006, 1007 causes the vibrating arm segments on both the sides of the through-hole 1005 to expand and contract in an opposite phase to each other in the vibrating arm section 1003. As such, the vibrating arm section 1003 vibrates in a bending mode. The same can be applied to the vibrating arm section 1004.
In the tuning-fork type quartz vibrator 1001 disclosed in Patent Document 1, there are provided a plurality of side bars 1008 in a region where the through-holes 1005 are provided.
Patent Document 1: Japanese Patent No. 3900513.
In the tuning-fork type quartz vibrator 1001, the vibrating arm segments on both the sides of the through-hole 1005 expand and contract in opposite phase to each other in the vibrating arm sections 1003 and 1004, and the vibrating arm sections 1003 and 1004 each vibrate in a bending mode. In the vibrating arm sections 1003 and 1004, providing the side bars 1008 increases the transmissibility of stress of expansion and contraction between the vibrating arm segments on both the sides of the through-hole 1005. In addition, mechanical strength is enhanced by the side bars 1008.
However, in the above tuning-fork type quartz vibrator 1001, a vibration form of the bending mode is deformed in some case even if the side bars 1008 are provided. Because of this, there are cases in which favorable vibration characteristics cannot be obtained.